Grouser shoe and fabrication method

ABSTRACT

A grouser shoe for track drives commonly utilized by industrial and commercial equipment (e.g., bulldozers, backhoes, cranes, etc.) comprising a supportive pad and a ground engaging bar, the ends of such bar being bent to form wings, and method of manufacture thereof. The center portion of the bar provides the primary transmission of driveforce from the vehicle to the ground, while the wings provide for significant reduction in vibration, facilitate steering, provide easier turning, and extend the service life of the grouser shoe.

FIELD TO WHICH THE INVENTION RELATES

Grouser shoes are used on bulldozers, backhoes, cranes, and otherdevices for providing individual segments to the crawler tracks thereof.This invention is directed to a grouser shoe with end wings and methodsfor fabricating same.

BACKGROUND OF THE INVENTION

Ground engaging track drives with grouser shoes are utilized forbulldozers, backhoes, cranes, and other industrial and commercialequipment. The purpose of these ground engaging track drives is tophysically support the heavy equipment over a significant contact areawhile also providing for a reliable, long-life driving engagement withthe ground on which the device is utilized. As an example of the former,on a large bulldozer the net pressure of the bulldozer is reduced tothat similar to a grown man standing on tip toes. As an example of thelatter, these devices are used to drivingly engage a wide variety ofsurfaces, ranging from rock in an industrial mine to light sand/soil inconstruction of a road. The track drives are typically optimized foreach utilization in consideration for the type of equipment, the natureof the power to the ground, the surface on which the equipment will beutilized, and other factors. Typically, the base section supports theequipment and the bar provides traction. As the bar penetrates theearth, it is subject to wear over time due to slippage or contact withhard surfaces, such as rock. The materials of which the grouser shoe ismanufactured are also important, both for wear resistance, powertransference to the surface and potential damage to the surface. Theformer is typically accomplished by the relatively flat base or padsection of the shoe and the latter by a bar member which extends offfrom the pad surface.

Although industrial procedures for producing grouser shoes in single andmultiple part construction of varying shapes and hardness are known,relatively little has been accomplished in recent years in respect tobreakthrough construction techniques or in fundamental design change.

Design variations have been limited by the described manufacturingmethods and otherwise.

SUMMARY OF THE INVENTION

It is an object of this invention to cost less than a cast shoe of amaterial such as manganese;

It is a further object of this invention to increase the service life ofgrouser shoes;

It is another object of this invention to increase the operator controlof devices using grouser shoes;

It is yet another object of this invention to provide for a morecomfortable operating environment to operators;

It is an object of this invention to differentially harden the variouscomponents of a grouser shoe; and,

It is still a further object of this invention to enhance turningperformance of devices including grouser shoes.

Other objects and a more complete understanding of the invention may behad by referring to the drawings in which:

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a grouser shoe including the wings ofthe invention;

FIG. 2 is a cross-sectional view of a bar of FIG. 1;

FIG. 3 is a contrast between driving forces on a straight bar and thebar of FIG. 2;

FIG. 4 is a representational drawing of possible differential angularformation of the individual wings of a given grouser shoe;

FIG. 5 is a flow chart utilized in the design of the bar of FIG. 2;

FIGS. 6-8 are top views of the grouser shoes of FIG. 1 duringmanufacture;

FIGS. 9-11 are respective end views of the three FIGS. 6-8 respectively;

FIG. 12 is a flow chart utilized in the manufacture of the grouser shoeof FIG. 1;

FIGS. 13-15 are top views of the grouser shoes of FIG. 1 duringalternate manufacture;

FIGS. 16-18 are respective end views of the three FIGS. 13-15respectively;

FIG. 19 is a flow chart utilized in the alternate manufacture of thegrouser shoe of FIG. 1; and,

FIG. 20 is an alternate embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention of this application relates to an improved grouser shoe ofa unique configuration together with a method of manufacture thereof.

The present invention relates to a grouser shoe 10 which has a pad 20and a bar 40 (FIG. 1).

The shoe itself is for engaging the ground in order to provide thesupport and drive for a tracked vehicle. Typically this tracked vehicleis a bulldozer or a heavy loader, although it is suitable for use withother forms of tracked vehicles.

The size, shape, and configuration of the shoe is selected in view ofthe particular tracked vehicle with which the shoe is to be utilized.This will differ from device to device as well as manufacturer tomanufacturer. The present shoe is to be utilized with a tracked vehiclehaving a sprocket-type drive mechanism through an intermediate integraldrivelink with additional location/flotation rollers (not shown). Thesprocket drive can be a three point with one high sprocket and twoidlers or a more conventional one sprocket and one idler configuration.In either case flotation rollers or other intermediate means areutilized to physically support the weight of the vehicle substantiallyequally across the ground engaging portion of the track.

The pad 20 provides for the basic weight bearing function of the shoe10. This transfers the physical weight of the vehicle to the ground overa large area. The pad in addition provides for the interconnectionbetween the drivelinks 60 and the later described bar 40. This pad 20 istypically a substantially flat piece 21 having a top surface 22, abottom surface 24, a leading edge 26 and a trailing edge 27.

The top surface is for providing the surface area for the physicalsupport of the tracked vehicle in addition to providing aninterconnection with the later described bar 40.

The size of the top surface 22 of the pad 20 is dependent upon the size,weight, power and capabilities of the tracked vehicle. This typically isunder the control of the manufacturer of the machine who optimizes agiven track surface area to such machine and usage. For example theaggregate surface area of all of the pads 20 in contact with the groundmay be such that on a extremely large bulldozer the net pressure persquare inch is on the order of 15 PSI (although obviously this could bevaried upward or downwards dependent on the use with which the machineis to be utilized). In general softer ground (sand) needs more surfacearea than harder ground (rock).

In addition to providing the flotation for the tracked vehicle, the topsurface 22 also provides a physical mounting location for the laterdescribed bar 40. This connects the bar 40 to the shoe 10 as well asproviding for the driving interconnection therebetween.

The bottom surface 24 of the pad 20 is utilized primarily tointerconnect the pad 20 to the drivelink 60 located on the undersidethereof. This drivelink serves to continuously interconnect thesequential shoes together so as to form a continuous length of track.The drivelink 60 shown (FIG. 20) in addition serves as the drivememberbetween the motor of the tracked unit and the continuous length oftrack. Typically floatation rollers in contact with the bottom surface24 of the shoe, directly or through the drivelinks, interconnect theshoes with the tracked vehicle so as to pass the ground support forcesbetween the shoe and the vehicle.

The drivelink 60 itself is again typically under the control of themanufacturer who ideally optimizes a particular drivelink system to aparticular tracked vehicle. The interconnection between the pad 20 andthe drivelink 60 will vary dependent upon the overall design of theunit. Since the interconnections between the individual drivelinks aretypically repairable (such as by exchange of pins/bushings etal) whilethe pads are typically replaceable (new/remanufactured units), the pads20 are preferably releasably connected to the drivelinks 60. In theparticular embodiment disclosed, this interconnection is provided by aseries of bolts 65 (phantom form in FIG. 1) extending through a seriesof partially recessed bolt holes 29 extending through the flat piece 21of the pad. This interconnection allows each individual pad 20 to beseparated from the continuous length of track without compromising theintegrity thereof (i.e., the pads 20 can be replaced one at a time witha minimum of difficulty). The recess 30 allows for more precise fit ofthe bolts 65 to the top surface 22 by insuring a reliable flat plane forthe underside of the bolts. This also aids in the uniformity of the bolttightening torque between holes and between shoes, The recess alsopermits a more compact shoe (or larger bolts) by cutting away theleading edge. With other types of tracked vehicles, otherinterconnections between the pad 20 and drivelink 60 may be appropriate.This would include other forms of releasable or permanentinterconnections. The type of interconnection would be dependent uponthe expected service longevity of the shoes and their various componentsas well as the longevity of the tracked vehicle itself. In general, thelonger the vehicle lasts and the more the bar wears from driving themachine, the more replaceable the pads 20 should be.

The leading 26 and trailing 27 edges of the pad 20 are designed tofacilitate ground engaging on soft surfaces as well as increasing theoverall cooperation between adjoining shoes. For example, in thepresently disclosed preferred embodiment the leading edge 26 is formedat an upward angle while the trailing edge 27 is formed at a downwardangle. This provides for a sand trap area at the top surface 22 betweenthe back of the leading edge 26 and the later described bar 40. Thisalso allows the pads 20 of two consecutive shoes to slightly overlapwithout interference. This not only creates pockets to trap soft groundbut also creates a seamless ground engaging surface for a consecutivelength of track. It in addition aids in the prevention of the migrationof contaminants through the track to the drivelinks 60 and associateddrive components. This facilitates soft ground drive engagement as wellas lengthening the service life of the track betweenlubrication/cleaning/maintenance. Further these edges 26, 27 strengthenthe bending strength of the flat piece 21 of the pad 20. The upwardextension of the pad in addition aids slightly to the driving connectionto the ground, and this at a location slightly displaced from the bar(the downward extension does also but to a marginal degree).

Note that in the embodiment disclosed the overlap between consecutivepads also provides for the possibility of physical contact between thetrailing edge 27 and the drivelink 60 at its bolted joint with the pad20. For this reason cutouts 31 are formed in the trailing edge 27 so asto prevent contact problems at this location (directly or indirectly viacontaminant buildup). Note that if desired other cutouts could beincluded in the pad 20 for various other purposes.

The preferred embodiment disclosed includes bolt protectors 33 on thetop surface 22 of the pad 20 (FIGS. 1, 20). A wear bar 36 may also beincluded (FIG. 20). Both of these are replaceable separately of theremainder of the shoe if desired.

The bolt protectors 33 extend upwards off of the top surface 22 toprotect the heads of the bolts 65 and reduce wear. They reduce thephysical damage thereto by rocks and other debris. They also slow downthe compaction of smaller contaminants into the bolt holes 29 andrecesses 30 surrounding such heads.

In the preferred embodiment disclosed the bolt protectors 33 are locatedoutside of each pair of bolt holes displaced substantially parallel tothe axis therebetween. Leading, trailing and/or inside locations couldalso be utilized.

The wear bar 36 extends upwards from the leading edge 26 of the topsurface 22 to reduce the physical wear thereon (FIG. 20). This isparticularly so for the upper end 37 of such edge 26, this end 37 beingthe highest point of the pad 20. Further the wear bar 36 can be replacedrelatively independently of the rest of the shoe 10.

In the preferred embodiment disclosed the wear bar 36 is located at theend 37 of the leading edge 26. Further the bolt protectors 33 are alsoextended forwardly over the leading edge 26 to the wear bar 36 attachedthereto. This causes the bolt protectors to reinforce the leading edge26 (primarily against flexing) and the wear bar 36 (primarily againstdisplacement).

The bar 40 extends upwardly off of the top surface 22 of the pad 20.This bar forms the primary ground engaging drive interconnection for theshoes 10 of the tracked vehicle. These bars 40 thus complete the driveinterconnection from the vehicles drive sprocket through the drivelinksand pads to the ground. In situations involving hard surfaces the bar 40may additionally physically support the tracked vehicle (up to theexclusion of the remainder of the shoe) (i.e., surfaces having astrength approaching that of the bar, for example on rock).

In the preferred embodiment disclosed, the bar 40 has two wings 46, 51.

The bar 40 provides for the primary transmission of driveforce from thevehicle to the ground. This provides for a relatively efficient transferof force at this particular location (aided by the closure of the wingsas later described). This strengthens the interconnection therebetweenas well as reducing fatigue separation concerns. This bar is preferablysubstantially perpendicular to the top surface of the pad 20.

The particular bar 40 is disclosed with an optional differential raisedsection 44 substantially co-extensive with the center thereof (dashedlines in FIG. 1; solid lines in FIG. 20). This optional center section44 provides for greater penetration into the ground at this particularlocation. In addition, it concentrates the weight of the vehicleinitially at this center section, thus allowing for a sequentialdifferential application of force across the length of the bar 40 inengagement with the ground. This facilitates the penetration movement ofthe bar thus to allow the support forces to be absorbed by the flatpiece 21 of the pad 20. It also reduces the pressure on the outside endsof the bar 40. It is preferred that this center section be over therails of the drivelink 60, these latter proving the primary support forthe pads 20. This provides for an efficient load transfer while alsoreducing wear on the drive link together with its pins and bushings.

The two wings 46, 51 are designed to work with the center 41 of the barin the drive and support of the tracked vehicle. These wings provide fora significant reduction in vibration, will facilitate the steering,provide easier turning and less noise in addition to extending the inservice life of the shoes 10.

The wings accomplish this due to a series of attributes, theseattributes most apparent in contrast to a conventional straight bar typedevice. These advantages include greater longitudinal contact, animpediment to flow by the ends, increase tip longevity and greaterapplication of driving force in any turn.

In respect to the greater longitudinal contact with the ground, thewings extend diagonally off of the center section of the bar. Thisspreads the loading of the bar over a greater effective longitudinalarea than otherwise. For example in the preferred embodiment the newlongitudinal contact 70 area is significantly longer than the oldcontact area 71 (the latter being co-extensive with the width timeslength of the bar) (FIG. 2). This lengthens the longitudinal contactarea significantly. This is important on the harder surfaces because itspreads the support loading of the bar 40 over a greater area of the pad20. This reduces load induced bending of the pad 20 (from a line inconventional unit to an enlarged area).

In respect to the resistance of the flow by the ends, the inner surface47 of each of the wings creates a pocket 50 behind the bar 40. Thisforces any residual blowby to pass backwards through an increasedpressure contact area, thus resisting the flow of material passing bythe bar.

In respect to increased tip longevity, the leading edge 54 is protectedby the outer end 55 of the wings and the trailing edge 53 at the back ofthe bar 40. For this reason, a significantly greater amount of materialhas to be worn away before the effective total length of the bar 40 isdecreased.

In respect to force on turns a conventional bar, being straight, allowsthe passage 56 of ground material and debris past the end of the bar(FIG. 3A). In contrast, in the present invention, due to the wings apocket is created to impede passage 57 (FIG. 3B). The effective drivingturn surface 49 is greater than the length of each individual wing dueto the fact that each wing will form a pocket 50 which will trapmaterials, thus extending the effective length of the surface at theselocations.

Each wing 46, 51 has a bend between the outer end 48 and the center 41of the bar. This bend is preferably designed in consideration of thewidth of the shoe, the number of shoes on the ground together with theuse cycle of the tracked vehicle with which the shoe 10 is to beutilized. This may include a shoe with a differential between the bendfor one wing 46 versus that of the other wing 51.

The angles of the wings are selected through a process representative ofthe tracked vehicle and its operation. After determining the width ofthe shoes and the numbed of shoes on the ground, these steps includeascertaining the duty cycle of the machine 80, quantifying the usage 81,differentiating between the size of the device 82, the selection of theangles and shape 83 and the utilization of such shapes.

In reference to the width of the shoes and the number of shoes on theground, in general the greater the width and/or the greater the numberof shoes on the ground, the less the angle and length of the wings.While this is somewhat paradoxical, it does recognize that eitherreduces the effectiveness of wings. For example very wide bars functionincreasingly as flat engagement pads (i.e., they begin to act similar tohard rubber street pads on concrete). An additional example increasingthe number of bars will function increasingly as a single surface(albeit long and maybe skinny) (i.e., it begins to act similar to theaccessory for Bobcat type wheel loaders that utilize a single band ofcontinuous rubber about two spaced wheels, one band per side).

The ascertaining of the particular duty cycles involves a mathematicalcalculation to determine how a particular tracked vehicle will be or isutilized. If the application is a specific one, for example a long faceloader in a open pit mine or a bulldozer providing a contour to largefields for a shopping mall, the duty cycle of the machine can becalculated. The former will necessitate a high degree of mobility whilethe latter will necessitate primarily steering corrections. These definethe expected turning point and radius for the particular vehicle (forexample see FIG. 4).

The second step of the procedure is to quantify the duty cycles; that isto make a decision that based on this particular duty cycles (i.e., a)90% forward; b) 50% forward, 30% left side turn, 20% right side turn; c)etc.). It is preferred to optimize the forces on the particular type ofoperation. This involves examining how the tracked vehicle will beutilized, and more particularly what the power cycling will be. As amatter of drive efficiency, tracked machines are typically designed forground engaging drive in a straight direction. For this reason theprimary duty cycle quantification is the amount of the angle for each ofwing bend and the relative percentage of the length of each wing versustotal bar length. In general the greater the turning under load thegreater both the angle and percentage will be, with any potentialdifferential between wings primarily based on the width of the vehicleand the turning cycle thereof (due to differing radians to the point ofturn as later set forth). For example most bulldozers operate to applyfull ground engaging power in the forward direction, whether with bladeor ripper bar(s). This application, being subject to many singledirection subtle steering corrections under load could utilize wingsequally angled with minor angling at the ends of the bar and a smallpercentage of wing length. However a tracked loader may need most of itsmovement power in a rotating direction at a fraction of available totalunit power: the breakout/lifting power of its bucket is its primaryengine load. This loader application, being subject to forward andreverse major direction changes at a lower load at greater speeds thanthe bulldozer, could have the wings with major angling and a majorpercentage of length for both wings. Differential angling is moreappropriate for this latter due to the higher frequency of major turningmaneuvers. Note that in both instances bending of the wings for reverseground engaging power should not be necessary. The reason for this isthat the reverse power in both is a fraction of the peak forward power.

The next step is to differentiate between the various sides of thetracked vehicle. This would include consideration of the track spacingand that a particular vehicle may turn in either direction in asymmetrical fashion or that the machine may turn left more often thanright unsymmetrically. In the optimum embodiment, not only applicationspecifics, but also operator preferences would be incorporated into thiscalculation. Certain operators prefer to cycle left while otheroperators prefer to cycle right.

The next step is to select the angles in shape of the wings suitable forthe particular operation of the tracked vehicle. This is mostly amanufacturing decision on what the angles and shape actually will be.Again the selection of the angles has been previously discussed and itmay be appropriate in certain applications to include a differentialbend across the entire length of the wing instead of at its intersectionwith the center section. This would allow the inclusion of many surfaces49, each suitable for a particular operating condition of the machine.

The last step is to utilize the angles and shape into the actual bar ofthe shoe 10. This can be in the initial manufacture of the shoe and/orin the retrofit of a particular machine. This latter would includerecognition of the fact that the operating conditions of the particularmachine may vary over the service life of the machine and that thusdiffering geometry would be appropriate for the shoes of the particulartracked vehicle dependent upon the operation thereof.

The inner wing may be differentially angled in respect to the outerwing. This would be of particular application wherein the trackedvehicle had a high frequency of significant turning maneuvering. (Thisis subject to the limitation as previously set forth that the greaterthe width of the shoe and the greater the number of shoes on the groundthe less effective differential angling would be.)

The differential angling does not have to be uniform for every shoe.However, as a practical measure it is preferred that common angling beutilized for every shoe on a given track. This eases initial manufactureand repair. It is further preferred that the differential angling bedetermined by the geometry of a shoe in the middle of the track sectionbefore the midpoint of a given track in respect to the expected medianturning point and radius thereabout.

For an example, the track 12 of the vehicle may have a very high dutycycle turning around the point 17 (see FIG. 4). Under this particularcondition the outer wing will be moving forward in respect to the centerof the bar. For this reason it is preferred that the angle 13 of theouter wing be different than the angle 15 of the inner wing. In respectto the angle of the outer wing, because the bar 40 at this particularpoint is moving forward relative to the remainder of the bar, anyextension of the wing beyond a line perpendicular to a radian 14 throughsuch wing will cause drag. It is therefore preferred that this angle 13be 90°+/−20° in respect to this radian. This will cause the shoe 10 toeffectively eliminate any drag conditions in respect to the wing at thisend of the bar.

In respect to the angle of the inner wing 15, this angle is important toproviding the forward motive ground engaging force in respect to theshoe as described in respect to the turn surface 49. For this reason,the angle 15 between the radian 16 extending between the inner wing andthe point 17 is preferably equal to an angle parallel to such radian(again +/−20°). The reason for this is that the angle of deviation willvary the phantom turn surface 49 as previously described in respect tothis particular turn around point 17. In the example, this surface 49 ispreferably increased until it is parallel in respect to the radian 19 tothe median of the center section 41 through the midpoint of the bar 40(i.e., it is not just the angle of the inner wing).

While the angles 13 and 15 are being set forth in this example exemplifythat the geometry of a particular tracked vehicle in respect to aparticular turn around point 17, it is to be realized that very fewmachines operate in steady state turning conditions: every machine has acertain duty cycle including a set percentage of various directionaloperation. For example, a tracked loader in a mine will typically have ahigh frequency of turns between a wall surface and the loading of ahopper/box of some nature directly behind the tracked vehicle. Thisoperation will necessitate a minimum of straight, forward and backoperations while necessitating a high frequency of swiveling around thecentral point of the tracked vehicle in order to accomplish the typical180° turn duty cycle for the load/transport/dump/return operationsnecessary in the closed confined areas of a mine. However, a trackedblade bulldozer operating in an open area to grade a parking lot for asupermall will have very few significant degree turns with instead ahigh frequency of minor steering corrections in a single direction. Inthe former, the angle 13 of the outer wing will be more highlydifferentiated than the angle 15 of the inner wing. Point 17 in the mostcases will be close to (or even within the width of) the trackedvehicle. However, in the case of the latter, point 17 will be anextended distance from the tracked vehicle. Indeed, sufficiently farthat the two angles 13, 15 could, from a manufacturing standpoint, bemade equal without significant compromise to the efficiently ofoperation of the particular shoe. This is especially true consideringthe blade adjustments available to the operator.

The materials of the shoe and its dimensions, for example the length andwidth of the flat piece, are preferably selected dependent on theparticular application. The specific grouser shoe 10 disclosed isdesigned to be used with Caterpillar models D7 through D11N and KomatsuD85 through D555. It is substantially rectangular in shape, havingangled leading and trailing edges 26, 27 as described previously. Thewidth of the grouser shoe 10 is determined by the manufacturer of thetracked vehicle, and is typically uniform. The length of the flat piece21 is typically about 70% of the width of the shoe 10. The length of theleading edge 26 is typically about 15% of the width, while the length ofthe trailing edge 27 is typically about 10% of the width of the shoe 10.The overall length of the grouser shoe 10 is typically between 8-14″with a width of 12-20″. The thickness of the pad in the preferredembodiment typically may vary between 0.75-1.25″.

The pad 20 is preferably manufactured of 10B35 manganese alloy ofhardness 35-40 Rc while the bar 40 is preferably 10B35 manganese alloydifferentially hardened, having a hardness of 50-52 Rc for 75% at itsextremity and 30-40 Rc at its joint with pad 20 (this later tofacilitate welding to the pad 20). The particular bolt protector is 1″high and 1.5″ wide extending from the bar to the wear bar. Theparticular wear bar is 1″ high and 1″ wide extending for the width ofthe pad. The bar 40 has a length approximately equal to the width of theshoe with a uniform thickness between 1-1.5″. The height of the wing ispreferably in the range 3.75-4.75″. The width of the center 41 of thebar 40 is some 40-60% of the width of the shoe with a height equal tothat of the wings. The optional raised center section would extend some0.75-1″ upwards. The wings are both angled from 10° to 30° in an exampleequal angled unit. (One may be angled 0-40° while the other is angled20-60° in the differential angled unit.) The combined length of thewings added to the center total the width of the shoe subject to anoffset between the edge of the pad 20 and the bar 40 of about 0-0.5″.

The particular shoe 10 disclosed is, in addition to its unique geometry,subject to a unique manufacturing operation.

It has been determined by theoretical analysis and by operationalexperience that it is desirable to have a pad with a low hardness factorfor maximization of toughness and for minimization of breakage. Instandard practice, where one-piece construction is the rule, the abilityto obtain this characteristic of toughness has been thought of asmutually incompatible with the incorporation of a high hardness factorin the bar.

One aspect of one embodiment of the invention described herein allowsfor incorporation of the most desirable features in both the pad and thebar by virtue of multiple component construction. The preferredembodiment comprises a grouser shoe wherein the pad portion is of ahardness sufficient to provide a tough, resilient structure, while thebar extending therefrom is differentially hardened. The connectingportion of the bar is of substantially the same hardness as the pad toallow for welding of the two components, while the balance of the barbecomes progressively harder as the extremity of the bar is approached,the extremity being of a hardness sufficient to substantially resistwear erosion.

This two piece construction is provided by the following manufacturingtechnique.

The manufacturing of a two piece shoe includes initial formation of thepad 22, preferably by rolling or press forming of a piece of steel, anda separate bar 40 (being straight a cut off from a length of steel issufficient) (FIGS. 6,7,9 10 and 200 in FIG. 12). The next step of theprocedure is to bend the ends of the bar 40 to create the previouslydescribed wings 46, 51 (201 in FIG. 12). The length of the wings at anygiven end can be different from the other end, as can the angle betweenthe wing 46, 51 and the center 41. Note that this technique allows forvarious configurations of the bar as previously described herein. Whileaccomplished in a wide variety of ways, simple mechanical or hydraulicpressure and a single bend are preferred for manufacturing simplicity.

The various parts of the shoes are treated in order to alter thehardness/structure of the steel (202 in FIG. 12). In that the treatingpreferably involves raising the hardness of the bar 40 differentially inrespect to the pad 20 it is preferred that such treatment occur prior tothe attachment of the bar to the pad. The treatment typically increasesthe hardness of the outer edge of the bar so as to increase thelongevity thereof, preferably to match the longevity of the pad 20. Inthe embodiment disclosed, it is preferred that the pad has a Rockwellhardness on the range of 30-40 Rc while the bar 40 has a hardnessbeginning approximately equal to that of the pad 20 near its jointtherewith and increasing substantially uniformly to perhaps 50-55 Rc atthe outer edge including the raised section 44 at the center thereof.This, under certain operating conditions, lengthens the service life ofthe bar 40 to substantially equal that of the pad 20.

After the components have been treated, the bar 40 is positionedproperly on the pad 20 (FIG. 7, 10). The bar is then welded or otherwiseaffixed to the pad 20 in order to make the bar integral thereto (FIGS.8, 11 and 203 in FIG. 12). Welding is preferred for this connection dueto the continuation of similar materials across the junction between thepad and the wings at this location. This strengthens this joint andreduces weld fracturing. The wear bar and bolt protectors would also bewelded to the pad 20 at this time.

At this time the drive link is connected to the pad 20 (204 in FIG. 12).This completes the manufacturing of the shoe 10. Note, however, thatsince the hardness of the drive link equals that of the pad thisconnection can occur at any time.

An alternate method of manufacturing includes initial formation of ashoe having an integral pad and bar (FIGS. 13-19). This is preferablyformed by rolling a single piece of steel (FIGS. 13, 16 and 100 in FIG.19). This integral piece of steel could be formed of a steel having asingle structure and hardness. It can also be a member made ofdifferential materials which have been drawn or otherwise fusedtogether. The former provides simplicity while the latter allows the padand bar to have differential qualities on initial formation.

The next step of the procedure is to shear the end(s) of the bar fromthe pad (101 in FIG. 19). This frees the ends of the bar for the bendingprocess to create the previously described wings 46, 51 by making theseends no longer integral with the pad for the distance approximatelyequal to the length of the wings (FIG. 16). The length of the shear atany particular end can be different from the other end (note that inthis preferred embodiment the center 41 of the shoe remains integralwith the pad 20. This strengthens this critical joint and eliminatesfatigue separation and other problems inherent in a manufactured rightangle joint).

The following step is to form bends at the sheared ends, such endshaving been separated from the bar by the previous step, in order tocreate the particular wing (FIGS. 14, 17 and 102 in FIG. 19). Note thatthe degree of angle may also differ between the two wings 46, 51described.

After the bends are formed, the wings are then welded or otherwiseaffixed back to the pad 20 in order to make the wings integral thereto(FIGS. 15, 18 and 103 in FIG. 19). Welding is preferred for thisconnection due to the continuation of similar materials across thejunction between the pad and wings at this location.

The various parts of the shoe (including bar) are then treated in orderto alter the hardness/structure of the steel (104 in FIG. 19). Thistreating preferably involves raising the hardness of the bar 40differentially in respect to the pad 20, particularly its outer edge. Itis preferred that this treatment occur after the reunification of theends of the bar back to the pad so as not to compromise this connection.

The drivelink 60 is attached to the bottom surface 24 of the pad 20 inorder to complete the shoe (105 in FIG. 19). In that the hardness of thepad 20 remains relatively constant (in contrast to the bar 40) thisconnection can occur at any time. It is again preferred, however, thatthis connection occur after the treatment of the pad/bar in order not tounduly compromise this manufacturing operation.

Although the invention has been described in its preferred form in acertain degree of particularity, it is to be understood that numerouschanges can be made without deviating from the invention as herein afterclaimed:

1. A grouser shoe for a tracked vehicle, the grouser shoe having a padand a bar with a center and an end, the shoe comprising the bar being ofuniform thickness and being integral with the pad, the bar extendingupwardly off of the pad to form the primary ground engaging driveconnection for the shoe, the center of the bar having a center straightsection with a center axis, the end of the bar having an end axis, saidend axis being angled in respect to said center axis to form a wing atthe end of the bar, and said wing forming a pocket to provide animpediment to flow by the end of the bar.
 2. The grouser shoe of claim 1wherein the bar has a second end and characterized in that the secondend has a second end axis, and said second end axis being angled inrespect to said center axis to form a second wing at the second end ofthe bar.
 3. (canceled)
 4. The grouser shoe of claim 1 characterized inthat the center of the bar has a center height, the end of the bar hasan end height, and said center height being greater than said endheight.
 5. (canceled)
 6. The grouser shoe of claim 1 characterized inthat the bar is formed separately from the pad, and the bar and padbeing joined to form the shoe.
 7. The grouser shoe of claim 1characterized in that the bar is formed separately from the pad andwelded onto the pad.
 8. The grouser shoe of claim 1 characterized inthat the bar is formed separately from the pad with part of the barbeing differentially hardened in respect to the pad.
 9. The grouser shoeof claim 7 characterized in that the bar is differentially hardened, andthe hardness of the bar approximating that of the pad along the jointthereto.
 10. The grouser shoe of claim 8 characterized in that the barjoints the pad at a joint and the pad has a Rockwell hardness, saidRockwell hardness being in the range of 30-40 Rc and the bar has ahardness substantially similar to that of the pad at its joint therewithwith its hardness increasing substantially uniformly outwardly therefromto substantially 50-55 Rc.
 11. The grouser shoe of claim 1 characterizedin that the bar and pad are formed as a single piece, with the end ofthe bar being sheared from the pad, bent, and then reattached to the padto form said wing.
 12. The grouser shoe of claim 11 characterized inthat the bar has ends, with said ends being sheared from the pad, bent,and then reattached to the pad to form the wings.
 13. The grouser shoeof claim 1 characterized in that the ends of the bar and pad is attachedby welding.
 14. A grouser shoe for a tracked vehicle, the grouser shoehaving a pad and a bar with a center and two ends, the shoe comprisingthe bar being of uniform thickness and being integral with the pad, thebar extending upwardly off of the pad to form the primary groundengaging drive connection for the shoe, the center of the bar having acenter straight section with a center axis, both ends of the bar havingend axes respectively, said end axes being angled in respect to saidcenter axis to form wings at the end of the bar, and said wings forminga pocket behind the bar to provide an impediment to flow by the ends ofthe bar.
 15. (canceled)
 16. A grouser shoe of claim 14 characterized inthat the bar has a center and two ends, said center and two ends eachhaving a height, and said center height being greater than said endheights.
 17. (canceled)
 18. The grouser shoe of claim 14 characterizedin that the bar is formed separately from the pad, and the bar and thepad being joined to form the shoe.
 19. The grouser shoe of claim 18characterized in that the bar is welded onto the pad.
 20. The grousershoe of claim 14 characterized in that the bar is differentiallyhardened in respect to the pad.
 21. The grouser shoe of claim 20characterized in that the bar is integral with the pad at a joint andhas a hardness, said hardness approximating that of the pad along thejoint therewith.
 22. The grouser shoe of claim 14 characterized in thatthe bar and pad are formed as a single piece, with the ends of the barbeing sheared from the pad, bent, and reattached integrally to the padto form said wings.
 23. The grouser shoe of claim 14 characterized inthat the ends of the bar are welded to the pad to reattach said wings.24. A grouser shoe for a tracked vehicle comprising a pad and anintegral bar, said bar having a center and two ends, the bar extendingupwardly off of the pad to form the primary ground engaging driveconnection for the shoe, said center having a straight section withcenter axis and each end having an end axis respectively, and said endaxes being angled in respect to said center axis of said straightsection to form wings, and said wings forming a pocket behind the bar toprovide an impediment to flow by the ends of the bar.
 25. In a grousershoe having a pad bolted to a drive link via a bolt, the improvement ofa bolt protector, and said bolt protector being attached to the pad nextto the bolt.
 26. In a grouser shoe having a pad with a leading edge anda grouser bar, the improvement of a wear bar, said wear bar beingdistinct from the grouser bar, said wear bar being replaceablyseparately attached to the pad at the leading edge thereof.
 27. Agrouser shoe having a bar with a center and an end, the improvement ofthe center of the bar being straight and end of the bar being angled inrespect to the center of the bar, said angling of the end of the barforming a pocket behind the bar to provide an impediment to flow by theends of the bar, and the bar extending upwardly off of the pad to formthe primary ground engaging drive connection for the shoe.
 28. A methodfor manufacturing a grouser shoe for a tracked vehicle, said methodcomprising forming a pad and forming a bar having a uniform thicknesswith a straight center section and two ends, the bar extending upwardlyoff of the pad to form the primary ground engaging drive connection forthe shoe, bending the ends of the bar in respect to said straightsection to form wings, and attaching the wings to the pad with saidwings forming a pocket behind the bar to provide an impediment to flowby the ends of the bar.
 29. A method of claim 28, said method comprisingthe forming of the pad separately from the forming of the bar.
 30. Amethod of claim 29 characterized in that the center and both ends of thebar are fixedly attached to the pad.
 31. A method of claim 28, saidmethod comprising forming the pad and bar as a single piece, andshearing the ends of the bar to form the wings.
 32. (canceled) 33.(canceled)
 34. A method for manufacturing a grouser shoe for a trackedvehicle, said method comprising forming a pad and forming a bar having auniform thickness with a center and two ends, the bar extending upwardlyoff of the pad to form the primary ground engaging drive connection forthe shoe, bending the ends of the bar to form wings, attaching the wingsto the pad, the wings of the bar being bent to form an angle between10-20° between such end and the center of the bar, and said wingsforming a pocket behind the bar to provide an impediment to flow by theends of the bar.
 35. (canceled)
 36. A method of claim 28 characterizedin that the grouser shoe is treated to alter the physical properties ofthe bar.
 37. A method of claim 36 characterized in that the grouser shoeis differentially heat treated such that the bar has a hardnesssubstantially similar to that of the pad at the joint therewith, andsaid hardness of the bar increases outwardly therefrom.
 38. A method ofclaim 37 characterized in that the pad has a Rockwell hardness, saidRockwell hardness being in the range of 35-40 Rc and the bar has aRockwell hardness, said Rockwell hardness being substantially 50-55 Rcat its outer edge.
 39. A method for manufacturing a grouser shoe for atracked vehicle, said method comprising forming a pad having a flatpiece, separately forming a bar of uniform thickness, the bar having acenter and two ends, the bar extending upwardly off of the pad to formthe primary ground engaging drive connection for the shoe, the centerhaving a center axis and each end having an end axis respectively,forming wings by bending the ends of the bar to produce an angle betweenthe center axis and each respective end axis to create a bar having a“C” shaped cross section, and attaching the bar to the pad with saidwings forming a pocket behind the bar to provide an impediment to flowby the ends of the bar.
 40. (canceled)
 41. A method of claim 39characterized in that the angle between the center axis and therespective end axis is between 10-20°.
 42. (canceled)
 43. A method ofclaim 39 characterized in that the grouser shoe is differentiallytreated such that the bar has a hardness substantially similar to thatof the pad at the joint therewith, and said hardness of the barincreasing outwardly therefrom.
 44. A method of claim 43 characterizedin that the pad has a Rockwell hardness of about 35-40 Rc and the barhas a hardness of substantially 50-55 Rc at its outer edge. 45.(canceled)
 46. (canceled)
 47. (canceled)
 48. (canceled)
 49. (canceled)50. (canceled)
 51. A method for manufacturing a grouser shoe for atracked vehicle, said method comprising forming a pad having a flatpiece with a leading edge and a trailing edge, the width of the flatpiece being substantially 60-80% of the length of the pad, the width ofthe leading edge being substantially 10-20% of the length of the pad,and the width of the trailing edge being substantially 5-15% of thelength of the pad, separately forming a bar of uniform thickness, thebar having a center and two ends, the center having a center axis andeach end having an end axis, respectively, forming wings by bending theends of the bar to produce an angle of substantially 10-20° between thecenter axis and each respective end axis creating a bar having a “C”shaped cross section, heat treating the pad to a hardness ofsubstantially 35-40 Rc and differentially treating the bar to a hardnessof substantially 50-55 Rc for 75% of its extremity and 35-40 Rc at itsinner edge for joining with the pad, attaching the bar to the flat pieceof the pad, said wings forming a pocket behind the bar to provide animpediment to flow by the ends of the bar, and the bar extendingupwardly off of the pad to form the primary ground engaging driveconnection for the shoe.
 52. (canceled)
 53. A method for manufacturing agrouser shoe, said method comprising forming a pad and forming a bar,the bar having a straight center and an end, the bar extending upwardlyoff of the pad to form the Primary ground engaging drive connection forthe shoe, including bending said end of the bar in respect to thestraight center of the bar to form a wing and attaching said wing tosaid pad with said wings forming a pocket behind the bar to provide animpediment to flow by the ends of the bar.